Absorbent negative pressure wound therapy dressing

ABSTRACT

Disclosed herein are several embodiments of a wound treatment apparatus employing glue on the backing layer of a wound dressing. In some embodiments, the glue limits saturation of an absorbent layer beneath the backing layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/273,053, filed Dec. 30, 2015, entitled ABSORBENT NEGATIVE PRESSUREWOUND THERAPY DRESSING. The content of the aforementioned application ishereby incorporated by reference in its entirety as if fully set forthherein. The benefit of priority to the foregoing application is claimedunder the appropriate legal basis, including, without limitation, under35 U.S.C. § 119(e).

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the present invention relate generally to the treatmentof wounds using negative pressure wound therapy, in particular theprevention of fluid absorption in selected regions of a negativepressure wound therapy dressing.

Description of the Related Art

The treatment of open or chronic wounds that are too large tospontaneously close or otherwise fail to heal by means of applyingnegative pressure to the site of the wound is well known in the art.Negative pressure wound therapy (NPWT) systems currently known in theart commonly involve placing a cover that is impermeable orsemi-permeable to fluids over the wound, using various means to seal thecover to the tissue of the patient surrounding the wound, and connectinga source of negative pressure (such as a vacuum pump) to the cover in amanner so that negative pressure is created and maintained under thecover. It is believed that such negative pressures promote wound healingby facilitating the formation of granulation tissue at the wound siteand assisting the body's normal inflammatory process whilesimultaneously removing excess fluid, which may contain adversecytokines and/or bacteria. However, further improvements in NPWT areneeded to fully realize the benefits of treatment.

Many different types of wound dressings are known for aiding in NPWTsystems. These different types of wound dressings include many differenttypes of materials and layers, for example, gauze, pads, foam pads ormulti-layer wound dressings. One example of a multi-layer wound dressingis the PICO dressing, available from Smith & Nephew, which includes asuperabsorbent layer beneath a backing layer to provide a canister-lesssystem for treating a wound with NPWT. The wound dressing may be sealedto a suction port providing connection to a length of tubing, which maybe used to pump fluid out of the dressing and/or to transmit negativepressure from a pump to the wound dressing.

However, in some wound dressings the absorbent layer fills up with fluidin an unpredictable, and often, non-uniform manner. It may be desirable,in some situations, to more easily prevent fluid from reaching certainareas of the absorbent layer or of the overall dressing. Currentdressings have limited and/or unsatisfactory methods of controllingfluid paths in the absorbent layer and/or throughout the dressing.

SUMMARY OF THE INVENTION

Embodiments of the present disclosure relate to apparatuses and methodsfor wound treatment. Some of the wound treatment apparatuses describedherein comprise a negative pressure source or a pump system forproviding negative pressure to a wound. Wound treatment apparatuses mayalso comprise wound dressings that may be used in combination with thenegative pressure sources and pump assemblies described herein.

According to some embodiments there is provided a wound treatmentapparatus for treatment of a wound site, the wound treatment apparatuscomprising: a wound dressing configured to be positioned over a woundsite, the wound dressing comprising: a backing layer having an uppersurface and a lower surface and defining a perimeter configured to bepositioned over skin surrounding the wound site, the backing layerincluding an opening; adhesive or glue located on an upper surface ofthe backing layer; and an absorbent layer configured to be positionedbetween the backing layer and the wound site.

In embodiments, the wound treatment apparatus may further comprise awound contact layer beneath the absorbent layer and sealed to thebacking layer. In certain embodiments, an apparatus may further comprisea source of negative pressure configured to be in fluid communicationwith the wound site through the wound dressing. The absorbent materialmay comprise a vertical hole positioned below the opening in the backinglayer. In particular embodiments, the wound treatment apparatus mayfurther comprise a fluidic connector. The glue may be positioned betweenthe backing layer and the distal end of the fluidic connector. Inembodiments, the glue may be positioned on the upper surface of thebacking layer spaced away from the fluidic connector. The glue may beconfigured to prevent passage of liquid within the absorbent layer. Incertain embodiments, the glue may be a cyanoacrylate adhesive.

in certain aspects, the glue is located on an upper surface of thebacking layer and positioned over the periphery of the absorbent layer.The glue may be positioned over one edge of the absorbent layer. Theglue may be positioned in a stripe across the width of the absorbentlayer, In embodiments, the glue is positioned in four stripes across thewidth of the absorbent layer. The glue may be positioned in a squarepattern around the distal end of the fluidic connector.

Any of the features, components, or details of any of the arrangementsor embodiments disclosed in this application, including withoutlimitation any of the pump embodiments and any of the negative pressurewound therapy embodiments disclosed below, are interchangeablycombinable with any other features, components, or details of any of thearrangements or embodiments disclosed herein to form new arrangementsand embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate.

FIG. 1B illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate.

FIG. 2A illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate.

FIG. 2B illustrates a cross section of an embodiment of a fluidicconnector connected to a wound dressing.

FIG. 3A is an image of an embodiment of a partially saturated wounddressing, comprising a ring of glue around the distal end of a fluidicconnector.

FIG. 3B is an illustration of an embodiment of a partially saturatedwound dressing, comprising a ring of glue around the distal end of afluidic connector.

FIGS. 4A-C are illustrations of embodiments of wound dressings withvarious patterns of glue.

FIG. 5 shows multiple images of embodiments of a wound dressing thatbecomes more saturated with dyed fluid over time.

FIG. 6 shows multiple cross-sectional micro-CTs of embodiments of wounddressings with glue on the backing layer.

FIG. 7 shows multiple scanning electron microscopy (SEM) micrographs ofembodiments of wound dressings with glue on the backing layer.

FIG. 8 shows multiple SEM micrographs of embodiments of wound dressingswith glue on the backing layer.

FIG. 9 shows multiple SEM micrographs of embodiments of wound dressingswithout glue on the backing layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments disclosed herein relate to apparatuses and methods oftreating a wound with reduced pressure, including a source of negativepressure and wound dressing components and apparatuses. The apparatusesand components comprising the wound overlay and packing materials, ifany, are sometimes collectively referred to herein as dressings.

Preferred embodiments disclosed herein relate to wound therapy for ahuman or animal body. Therefore, any reference to a wound herein canrefer to a wound on a human or animal body, and any reference to a bodyherein can refer to a human or animal body. The term “wound” as usedherein, in addition to having its broad ordinary meaning, includes anybody part of a patient that may be treated using negative pressure.Wounds include, but are not limited to, open wounds, incisions,lacerations, abrasions, contusions, burns, diabetic ulcers, pressureulcers, stoma, surgical wounds, trauma and venous ulcers or the like.Treatment of such wounds can be performed using negative pressure woundtherapy, wherein a reduced or negative pressure can be applied to thewound to facilitate and promote healing of the wound. It will also beappreciated that the wound dressing and methods as disclosed herein maybe applied to other parts of the body, and are not necessarily limitedto treatment of wounds. Certain embodiments of this application relateto a wound treatment apparatus employing a wound dressing and a fluidicconnector, and to methods of using the same.

It will be understood that embodiments of the present disclosure aregenerally applicable to use in topical negative pressure (“TNP”) therapysystems. Briefly, negative pressure wound therapy assists in the closureand healing of many forms of “hard to heal” wounds by reducing tissueoedema; encouraging blood flow and granular tissue formation; removingexcess exudate and may reduce bacterial load (and thus infection risk).In addition, the therapy allows for less disturbance of a wound leadingto more rapid healing. TNP therapy systems may also assist on thehealing of surgically closed wounds by removing fluid and by helping tostabilize the tissue in the apposed position of closure. A furtherbeneficial use of TNP therapy can be found in grafts and flaps whereremoval of excess fluid is important and close proximity of the graft totissue is required in order to ensure tissue viability.

As is used herein, reduced or negative pressure levels, such as −X mmHg,represent pressure levels relative to normal ambient atmosphericpressure, which can correspond to 760 mmHg (or 1 atm, 29.93 inHg,101.325 kPa, 14.696 psi, etc.). Accordingly, a negative pressure valueof −X mmHg reflects absolute pressure that is X mmHg below 760 mmHg or,in other words, an absolute pressure of (760−X) mmHg. In addition,negative pressure that is “less” or “smaller” than X mmHg corresponds topressure that is closer to atmospheric pressure (e.g.,−40 mmHg is lessthan −60 mmHg). Negative pressure that is “more” or “greater” than −XmmHg corresponds to pressure that is further from atmospheric pressure(e.g., −80 mmHg is more than −60 mmHg). In some embodiments, localambient atmospheric pressure is used as a reference point, and suchlocal atmospheric pressure may not necessarily be, for example, 760mmHg.

The negative pressure range for some embodiments of the presentdisclosure can be approximately −80 mmHg, or between about −20 mmHg and−200 mmHg. Note that these pressures are relative to normal ambientatmospheric pressure, which can be 760 mmHg. Thus, −200 mmHg would beabout 560 mmHg in practical terms. In some embodiments, the pressurerange can be between about −40 mmHg and −150 mmHg. Alternatively apressure range of up to −75 mmHg, up to −80 mmHg or over −80 mmHg can beused. Also in other embodiments a pressure range of below −75 mmHg canbe used. Alternatively, a pressure range of over approximately −100 mmHgor even −150 mmHg, can be supplied by the negative pressure apparatus.

In some embodiments of wound closure devices described herein, increasedwound contraction can lead to increased tissue expansion in thesurrounding wound tissue. This effect may be increased by varying theforce applied to the tissue, for example by varying the negativepressure applied to the wound over time, possibly in conjunction withincreased tensile forces applied to the wound via embodiments of thewound closure devices. In some embodiments, negative pressure may bevaried over time for example using a sinusoidal wave, square wave,and/or in synchronization with one or more patient physiological indices(e.g., heartbeat). Examples of such applications where additionaldisclosure relating to the preceding may be found include U.S. Pat. No.8,235,955, titled “Wound treatment apparatus and method,” issued on Aug.7, 2012; and U.S. Pat. No. 7,753,894, titled “Wound cleansing apparatuswith stress,” issued Jul. 13, 2010. The disclosures of both of thesepatents are hereby incorporated by reference in their entirety.

Embodiments of the wound dressings, wound dressing components, woundtreatment apparatuses and methods described herein may also be used incombination or in addition to those described in InternationalApplication No. PCT/IB2013/001469, filed May 22, 2013, published as WO2013/175306 A2 on Nov. 28, 2013, titled “APPARATUSES AND METHODS FORNEGATIVE PRESSURE WOUND THERAPY,” U.S. patent application Ser. No.14/418874, filed Jan. 30, 2015, published as US 2015/0190286 A1 on Jul.9, 2015, titled “WOUND DRESSING AND METHOD OF TREATMENT,” thedisclosures of which are hereby incorporated by reference in theirentireties. Embodiments of the wound dressings, wound treatmentapparatuses and methods described herein may also be used in combinationor in addition to those described in U.S. patent application Ser. No.13/092,042, filed Apr. 21 2011, published as US2011/0282309, titled“WOUND DRESSING AND METHOD OF USE,” and U.S. patent application Ser. No.14/715,527, filed May 18, 2015, published as U52016/0339158, titled“FLUIDIC CONNECTOR FOR NEGATIVE PRESSURE WOUND THERAPY,” the disclosuresof which are hereby incorporated by reference in its entirety, includingfurther details relating to embodiments of wound dressings, the wounddressing components and principles, and the materials used for the wounddressings.

Additionally, some embodiments related to TNP wound treatment comprisinga wound dressing in combination with a pump and/or associatedelectronics described herein may also be used in combination or inaddition to those described in International Application No.PCT/EP2016/059329, filed Apr. 26, 2016, published as WO2016174048 A1 onNov. 3, 2016, titled “REDUCED PRESSURE APPARATUS AND METHODS.”

The Wound Dressings of FIGS. 1A-2B

FIGS. 1A-B illustrate embodiments of a negative pressure wound treatmentsystem 10 employing a wound dressing 100 in conjunction with a fluidicconnector 110. Here, the fluidic connector 110 may comprise an elongateconduit, more preferably a bridge 120 having a proximal end 130 and adistal end 140, and an applicator 180 at the distal end 140 of thebridge 120. An optional coupling 160 is preferably disposed at theproximal end 130 of the bridge 120. A cap 170 may be provided with thesystem (and can in some cases, as illustrated, be attached to thecoupling 160). The cap 170 can be useful in preventing fluids fromleaking out of the proximal end 130. The system 10 may include a sourceof negative pressure such as a pump or negative pressure unit 150capable of supplying negative pressure. The pump may comprise a canisteror other container for the storage of wound exudates and other fluidsthat may be removed from the wound. A canister or container may also beprovided separate from the pump. In some embodiments, such asillustrated in FIGS. 1A-1B, the pump 150 can be a canisterless pump suchas the PICO™ pump, as sold by Smith & Nephew. The pump 150 may beconnected to the coupling 160 via a tube 190, or the pump 150 may beconnected directly to the coupling 160 or directly to the bridge 120. Inuse, the dressing 100 is placed over a suitably-prepared wound, whichmay in some cases be filled with a wound packing material such as foamor gauze. The applicator 180 of the fluidic connector 110 has a sealingsurface that is placed over an aperture in the dressing 100 and issealed to the top surface of the dressing 100. Either before, during, orafter connection of the fluidic connector 110 to the dressing 100, thepump 150 is connected via the tube 190 to the coupling 160, or isconnected directly to the coupling 160 or to the bridge 120. The pump isthen activated, thereby supplying negative pressure to the wound.Application of negative pressure may be applied until a desired level ofhealing of the wound is achieved. In some embodiments, the pump can beminiaturized and portable, although larger conventional pumps may alsobe used with the dressing 100. In some embodiments, the pump may beattached or mounted onto or adjacent the dressing 100.

In some embodiments, a source of negative pressure (such as a pump) andsome or all other components of the TNP system, such as power source(s),sensor(s), connector(s), user interface component(s) (such as button(s),switch(es), speaker(s), screen(s), etc.) and the like, can be integralwith the wound dressing. The wound dressing can include a cover layerfor positioning over the layers of the wound dressing. The cover layercan be the upper most layer of the dressing. In some embodiments, thewound dressing can include a second cover layer for positioning over thelayers of the wound dressing and any of the integrated components. Thesecond cover layer can be the upper most layer of the dressing or can bea separate envelope that encloses the integrated components of thetopical negative pressure system.

As shown in FIG. 2A, the fluidic connector 110 preferably comprises anenlarged distal end, or head 140 that is in fluidic communication withthe dressing 100 as will be described in further detail below. In oneembodiment, the enlarged distal end has a round or circular shape. Thehead 140 is illustrated here as being positioned near an edge of thedressing 100, but may also be positioned at any location on thedressing. For example, some embodiments may provide for a centrally oroff-centered location not on or near an edge or corner of the dressing100. In some embodiments, the dressing 100 may comprise two or morefluidic connectors 110, each comprising one or more heads 140, influidic communication therewith. In a preferred embodiment, the head 140may measure 30 mm along its widest edge. The head 140 forms at least inpart the applicator 180, described above, that is configured to sealagainst a top surface of the wound dressing.

FIG. 2B illustrates a cross-section through a wound dressing 100 similarto the wound dressing 100 as shown in FIG. 1B and described inInternational Patent Publication WO2013175306 A2, filed May 22, 2013,entitled “APPARATUSES AND METHODS FOR NEGATIVE PRESSURE WOUND THERAPY”,the disclosure of which is hereby incorporated by reference in itsentirety, along with fluidic connector 110. The wound dressing 100,which can alternatively be any wound dressing embodiment disclosedherein or any combination of features of any number of wound dressingembodiments disclosed herein, can be located over a wound site to betreated. The dressing 100 may be placed as to form a sealed cavity overthe wound site. In a preferred embodiment, the dressing 100 comprises atop or cover layer, or backing layer 220 attached to an optional woundcontact layer 222, both of which are described in greater detail below.These two layers 220, 222 are preferably joined or sealed together so asto define an interior space or chamber. This interior space or chambermay comprise additional structures that may be adapted to distribute ortransmit negative pressure, store wound exudate and other fluids removedfrom the wound, and other functions which will be explained in greaterdetail below. Examples of such structures, described below, include atransmission layer 226 and an absorbent layer 221.

As used herein the upper layer, top layer, or layer above refers to alayer furthest from the surface of the skin or wound while the dressingis in use and positioned over the wound. Accordingly, the lower surface,lower layer, bottom layer, or layer below refers to the layer that isclosest to the surface of the skin or wound while the dressing is in useand positioned over the wound.

As illustrated in FIG. 2B, the wound contact layer 222 can be apolyurethane layer or polyethylene layer or other flexible layer whichis perforated, for example via a hot pin process, laser ablationprocess, ultrasound process or in some other way or otherwise madepermeable to liquid and gas. The wound contact layer 222 has a lowersurface 224 and an upper surface 223. The perforations 225 preferablycomprise through holes in the wound contact layer 222 which enable fluidto flow through the layer 222. The wound contact layer 222 helps preventtissue ingrowth into the other material of the wound dressing.Preferably, the perforations are small enough to meet this requirementwhile still allowing fluid to flow therethrough. For example,perforations formed as slits or holes having a size ranging from 0.025mm to 1.2 mm are considered small enough to help prevent tissue ingrowthinto the wound dressing while allowing wound exudate to flow into thedressing. In some configurations, the wound contact layer 222 may helpmaintain the integrity of the entire dressing 100 while also creating anair tight seal around the absorbent pad in order to maintain negativepressure at the wound.

Some embodiments of the wound contact layer 222 may also act as acarrier for an optional lower and upper adhesive layer (not shown). Forexample, a lower pressure sensitive adhesive may be provided on thelower surface 224 of the wound dressing 100 whilst an upper pressuresensitive adhesive layer may be provided on the upper surface 223 of thewound contact layer. The pressure sensitive adhesive, which may be asilicone, hot melt, hydrocolloid or acrylic based adhesive or other suchadhesives, may be formed on both sides or optionally on a selected oneor none of the sides of the wound contact layer. When a lower pressuresensitive adhesive layer is utilized may be helpful to adhere the wounddressing 100 to the skin around a wound site. In some embodiments, thewound contact layer may comprise perforated polyurethane film. The lowersurface of the film may be provided with a silicone pressure sensitiveadhesive and the upper surface may be provided with an acrylic pressuresensitive adhesive, which may help the dressing maintain its integrity.In some embodiments, a polyurethane film layer may be provided with anadhesive layer on both its upper surface and lower surface, and allthree layers may be perforated together.

A layer 226 of porous material can be located above the wound contactlayer 222. This porous layer, or transmission layer, 226 allowstransmission of fluid including liquid and gas away from a wound siteinto upper layers of the wound dressing. In particular, the transmissionlayer 226 preferably ensures that an open air channel can be maintainedto communicate negative pressure over the wound area even when theabsorbent layer has absorbed substantial amounts of exudates. The layer226 should preferably remain open under the typical pressures that willbe applied during negative pressure wound therapy as described above, sothat the whole wound site sees an equalized negative pressure. The layer226 may be formed of a material having a three dimensional structure.For example, a knitted or woven spacer fabric (for example Baltex 7970weft knitted polyester) or a non-woven fabric could be used.

In some embodiments, the transmission layer 226 comprises a 3D polyesterspacer fabric layer including a top layer (that is to say, a layerdistal from the wound-bed in use) which is a 84/144 textured polyester,and a bottom layer (that is to say, a layer which lies proximate to thewound bed in use) which is a 10 denier flat polyester and a third layerformed sandwiched between these two layers which is a region defined bya knitted polyester viscose, cellulose or the like monofilament fiber.Other materials and other linear mass densities of fiber could of coursebe used.

Whilst reference is made throughout this disclosure to a monofilamentfiber it will be appreciated that a multistrand alternative could ofcourse be utilized. The top spacer fabric thus has more filaments in ayarn used to form it than the number of filaments making up the yarnused to form the bottom spacer fabric layer.

This differential between filament counts in the spaced apart layershelps control moisture flow across the transmission layer. Particularly,by having a filament count greater in the top layer, that is to say, thetop layer is made from a yarn having more filaments than the yarn usedin the bottom layer, liquid tends to be wicked along the top layer morethan the bottom layer. In use, this differential tends to draw liquidaway from the wound bed and into a central region of the dressing wherethe absorbent layer 221 helps lock the liquid away or itself wicks theliquid onwards towards the cover layer where it can be transpired.

Preferably, to improve the liquid flow across the transmission layer 226(that is to say perpendicular to the channel region formed between thetop and bottom spacer layers, the 3D fabric may be treated with a drycleaning agent (such as, but not limited to, Perchloro Ethylene) to helpremove any manufacturing products such as mineral oils, fats and/orwaxes used previously which might interfere with the hydrophiliccapabilities of the transmission layer. In some embodiments, anadditional manufacturing step can subsequently be carried in which the3D spacer fabric is washed in a hydrophilic agent (such as, but notlimited to, Feran Ice 30 g/l available from the Rudolph Group). Thisprocess step helps ensure that the surface tension on the materials isso low that liquid such as water can enter the fabric as soon as itcontacts the 3D knit fabric. This also aids in controlling the flow ofthe liquid insult component of any exudates.

A layer 221 of absorbent material is provided above the transmissionlayer 226. The absorbent material, which comprise a foam or non-wovennatural or synthetic material, and which may optionally comprise asuper-absorbent material, forms a reservoir for fluid, particularlyliquid, removed from the wound site. In some embodiments, the layer 10may also aid in drawing fluids towards the backing layer 220.

The material of the absorbent layer 221 may also prevent liquidcollected in the wound dressing 100 from flowing freely within thedressing, and preferably acts so as to contain any liquid collectedwithin the dressing. The absorbent layer 221 also helps distribute fluidthroughout the layer via a wicking action so that fluid is drawn fromthe wound site and stored throughout the absorbent layer. This helpsprevent agglomeration in areas of the absorbent layer. The capacity ofthe absorbent material must be sufficient to manage the exudates flowrate of a wound when negative pressure is applied. Since in use theabsorbent layer experiences negative pressures the material of theabsorbent layer is chosen to absorb liquid under such circumstances. Anumber of materials exist that are able to absorb liquid when undernegative pressure, for example superabsorber material. The absorbentlayer 221 may typically be manufactured from ALLEVYN™ foam, Freudenberg114-224-4 and/or Chem-Posite™ 11C-450. In some embodiments, theabsorbent layer 221 may comprise a composite comprising superabsorbentpowder, fibrous material such as cellulose, and bonding fibers. In apreferred embodiment, the composite is an airlaid, thermally-bondedcomposite.

In some embodiments, the absorbent layer 221 is a layer of non-wovencellulose fibers having super-absorbent material in the form of dryparticles dispersed throughout. Use of the cellulose fibers introducesfast wicking elements which help quickly and evenly distribute liquidtaken up by the dressing. The juxtaposition of multiple strand-likefibers leads to strong capillary action in the fibrous pad which helpsdistribute liquid. In this way, the super-absorbent material isefficiently supplied with liquid. The wicking action also assists inbringing liquid into contact with the upper cover layer to aid increasetranspiration rates of the dressing.

An aperture, hole, or orifice 227 is preferably provided in the backinglayer 220 to allow a negative pressure to be applied to the dressing100. The fluidic connector 110 is preferably attached or sealed to thetop of the backing layer 220 over the orifice 227 made into the dressing100, and communicates negative pressure through the orifice 227. Alength of tubing may be coupled at a first end to the fluidic connector110 and at a second end to a pump unit (not shown) to allow fluids to bepumped out of the dressing. Where the fluidic connector is adhered tothe top layer of the wound dressing, a length of tubing may be coupledat a first end of the fluidic connector such that the tubing, orconduit, extends away from the fluidic connector parallel orsubstantially to the top surface of the dressing. The fluidic connector110 may be adhered and sealed to the backing layer 220 using an adhesivesuch as an acrylic, cyanoacrylate, epoxy, UV curable or hot meltadhesive. The fluidic connector 110 may be formed from a soft polymer,for example a polyethylene, a polyvinyl chloride, a silicone orpolyurethane having a hardness of 30 to 90 on the Shore A scale. In someembodiments, the fluidic connector 110 may be made from a soft orconformable material.

Preferably the absorbent layer 221 includes at least one through hole228 located so as to underlie the fluidic connector 110. The throughhole 228 may in some embodiments be the same size as the opening 227 inthe backing layer, or may be bigger or smaller. As illustrated in FIG.2B a single through hole can be used to produce an opening underlyingthe fluidic connector 110 It will be appreciated that multiple openingscould alternatively be utilized. Additionally should more than one portbe utilized according to certain embodiments of the present disclosureone or multiple openings may be made in the absorbent layer and theobscuring layer in registration with each respective fluidic connector.Although not essential to certain embodiments of the present disclosurethe use of through holes in the super-absorbent layer may provide afluid flow pathway which remains unblocked in particular when theabsorbent layer is near saturation.

The aperture or through-hole 228 is preferably provided in the absorbentlayer 221 beneath the orifice 227 such that the orifice is connecteddirectly to the transmission layer 226 as illustrated in FIG. 2B. Thisallows the negative pressure applied to the fluidic connector 110 to becommunicated to the transmission layer 226 without passing through theabsorbent layer 221. This ensures that the negative pressure applied tothe wound site is not inhibited by the absorbent layer as it absorbswound exudates. In other embodiments, no aperture may be provided in theabsorbent layer 221, or alternatively a plurality of aperturesunderlying the orifice 227 may be provided. In further alternativeembodiments, additional layers such as another transmission layer or anobscuring layer such as described in US Patent Publication 2015/0190286A1, the entirety of which is hereby incorporated by reference, may beprovided over the absorbent layer 221 and beneath the backing layer 220.

The backing layer 220 is preferably gas impermeable, but moisture vaporpermeable, and can extend across the width of the wound dressing 100.The backing layer 220, which may for example be a polyurethane film (forexample, Elastollan SP9109) having a pressure sensitive adhesive on oneside, is impermeable to gas and this layer thus operates to cover thewound and to seal a wound cavity over which the wound dressing isplaced. In this way an effective chamber is made between the backinglayer 220 and a wound site where a negative pressure can be established.The backing layer 220 is preferably sealed to the wound contact layer222 in a border region around the circumference of the dressing,ensuring that no air is drawn in through the border area, for examplevia adhesive or welding techniques. The backing layer 220 protects thewound from external bacterial contamination (bacterial barrier) andallows liquid from wound exudates to be transferred through the layerand evaporated from the film outer surface. The backing layer 220preferably comprises two layers; a polyurethane film and an adhesivepattern spread onto the film. The polyurethane film is preferablymoisture vapor permeable and may be manufactured from a material thathas an increased water transmission rate when wet. In some embodimentsthe moisture vapor permeability of the backing layer increases when thebacking layer becomes wet. The moisture vapor permeability of the wetbacking layer may be up to about ten times more than the moisture vaporpermeability of the dry backing layer.

The absorbent layer 221 may be of a greater area than the transmissionlayer 226, such that the absorbent layer overlaps the edges of thetransmission layer 226, thereby ensuring that the transmission layerdoes not contact the backing layer 220. This provides an outer channelof the absorbent layer 221 that is in direct contact with the woundcontact layer 222, which aids more rapid absorption of exudates to theabsorbent layer. Furthermore, this outer channel ensures that no liquidis able to pool around the circumference of the wound cavity, whichcould seep through the seal around the perimeter of the dressing leadingto the formation of leaks. As illustrated in FIGS. 2A-2B, the absorbentlayer 221 may define a smaller perimeter than that of the backing layer220, such that a boundary or border region is defined between the edgeof the absorbent layer 221 and the edge of the backing layer 220.

As shown in FIG. 2B, one embodiment of the wound dressing 100 comprisesan aperture 228 in the absorbent layer 221 situated underneath thefluidic connector 110. In use, for example when negative pressure isapplied to the dressing 100, a wound facing portion of the fluidicconnector may thus come into contact with the transmission layer 226,which can thus aid in transmitting negative pressure to the wound siteeven when the absorbent layer 221 is filled with wound fluids. Someembodiments may have the backing layer 220 be at least partly adhered tothe transmission layer 226. In some embodiments, the aperture 228 is atleast 1-2 mm larger than the diameter of the wound facing portion of thefluidic connector 110, or the orifice 227.

In particular for embodiments with a single fluidic connector 110 andthrough hole, it may be preferable for the fluidic connector 110 andthrough hole to be located in an off-center position as illustrated inFIG. 2A. Such a location may permit the dressing 100 to be positionedonto a patient such that the fluidic connector 110 is raised in relationto the remainder of the dressing 100. So positioned, the fluidicconnector 110 and the filter 214 (described below) may be less likely tocome into contact with wound fluids that could prematurely occlude thefilter 214 so as to impair the transmission of negative pressure to thewound site.

Turning now to the fluidic connector 110, preferred embodiments comprisea sealing surface 216, a bridge 211 (corresponding to bridge 120 inFIGS. 1A-1B) with a proximal end 130 and a distal end 140, and a filter214. The sealing surface 216 preferably forms the applicator previouslydescribed that is sealed to the top surface of the wound dressing. Insome embodiments a bottom layer of the fluidic connector 110 maycomprise the sealing surface 216. The fluidic connector 110 may furthercomprise an upper surface vertically spaced from the sealing surface216, which in some embodiments is defined by a separate upper layer ofthe fluidic connector. In other embodiments the upper surface and thelower surface may be formed from the same piece of material. In someembodiments the sealing surface 216 may comprise at least one aperture229 therein to communicate with the wound dressing. In some embodimentsthe filter 214 may be positioned across the opening 229 in the sealingsurface, and may span the entire opening 229. The sealing surface 216may be configured for sealing the fluidic connector to the cover layerof the wound dressing, and may comprise an adhesive or weld. In someembodiments, the sealing surface 216 may be placed over an orifice inthe cover layer. In other embodiments, the sealing surface 216 may bepositioned over an orifice in the cover layer and an aperture in theabsorbent layer 220, permitting the fluidic connector 110 to provide airflow through the transmission layer 226. In some embodiments, the bridge211 may comprise a first fluid passage 212 in communication with asource of negative pressure, the first fluid passage 212 comprising aporous material, such as a 3D knitted material, which may be the same ordifferent than the porous layer 226 described previously. The bridge 211is preferably encapsulated by at least one flexible film layer 208, 210having a proximal and distal end and configured to surround the firstfluid passage 212, the distal end of the flexible film being connectedto the sealing surface 216. The filter 214 is configured tosubstantially prevent wound exudate from entering the bridge.

Some embodiments may further comprise an optional second fluid passagepositioned above the first fluid passage 212. For example, someembodiments may provide for an air leak may be disposed at the proximalend of the top layer 208 that is configured to provide an air path intothe first fluid passage 212 and dressing 100 similar to the suctionadapter as described in U.S. Pat. No. 8,801,685, filed Dec. 30, 2011,entitled “APPARATUSES AND METHODS FOR NEGATIVE PRESSURE WOUND THERAPY”the disclosure of which is hereby incorporated by reference in itsentirety.

Preferably, the fluid passage 212 is constructed from a compliantmaterial that is flexible and that also permits fluid to pass through itif the spacer is kinked or folded over. Suitable materials for the fluidpassage 212 include without limitation foams, including open-cell foamssuch as polyethylene or polyurethane foam, meshes, 3D knitted fabrics,non-woven materials, and fluid channels. In some embodiments, the fluidpassage 212 may be constructed from materials similar to those describedabove in relation to the transmission layer 226. Advantageously, suchmaterials used in the fluid passage 212 not only permit greater patientcomfort, but may also provide greater kink resistance, such that thefluid passage 212 is still able to transfer fluid from the wound towardthe source of negative pressure while being kinked or bent.

in some embodiments, the fluid passage 212 may be comprised of a wickingfabric, for example a knitted or woven spacer fabric (such as a knittedpolyester 3D fabric, Baltex 7970®, or Gehring 879®) or a nonwovenfabric. These materials selected are preferably suited to channelingwound exudate away from the wound and for transmitting negative pressureand/or vented air to the wound site, and may also confer a degree ofkinking or occlusion resistance to the fluid passage 212. In someembodiments, the wicking fabric may have a three-dimensional structure,which in some cases may aid in wicking fluid or transmitting negativepressure. In certain embodiments, including wicking fabrics, thesematerials remain open and capable of communicating negative pressure toa wound area under the typical pressures used in negative pressuretherapy, for example between 40 to 150 mmHg. In some embodiments, thewicking fabric may comprise several layers of material stacked orlayered over each other, which may in some cases be useful in preventingthe fluid passage 212 from collapsing under the application of negativepressure. In other embodiments, the wicking fabric used in the fluidpassage 212 may be between 1.5 mm and 6 mm; more preferably, the wickingfabric may be between 3 mm and 6 mm thick, and may be comprised ofeither one or several individual layers of wicking fabric. In otherembodiments, the fluid passage 212 may be between 1.2-3 mm thick, andpreferably thicker than 1.5 mm. Some embodiments, for example a suctionadapter used with a dressing which retains liquid such as wound exudate,may employ hydrophobic layers in the fluid passage 212, and only gasesmay travel through the fluid passage 212. Additionally, and as describedpreviously, the materials used in the system are preferably conformableand soft, which may help to avoid pressure ulcers and othercomplications which may result from a wound treatment system beingpressed against the skin of a patient.

Preferably, the filter element 214 is impermeable to liquids, butpermeable to gases, and is provided to act as a liquid barrier and toensure that no liquids are able to escape from the wound dressing 100.The filter element 214 may also function as a bacterial barrier.Typically the pore size is 0.2 μm. Suitable materials for the filtermaterial of the filter element 214 include 0.2 micron Gore™ expandedPTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628.Larger pore sizes can also be used but these may require a secondaryfilter layer to ensure full bioburden containment. As wound fluidcontains lipids it is preferable, though not essential, to use anoleophobic filter membrane for example 1.0 micron MMT-332 prior to 0.2micron MMT-323. This prevents the lipids from blocking the hydrophobicfilter. The filter element can be attached or sealed to the port and/orthe cover film over the orifice. For example, the filter element 214 maybe molded into the fluidic connector 110, or may be adhered to one orboth of the top of the cover layer and bottom of the suction adapter 110using an adhesive such as, but not limited to, a UV cured adhesive.

It will be understood that other types of material could be used for thefilter element 214. More generally a microporous membrane can be usedwhich is a thin, flat sheet of polymeric material, this containsbillions of microscopic pores. Depending upon the membrane chosen thesepores can range in size from 0.01 to more than 10 micrometers.Microporous membranes are available in both hydrophilic (waterfiltering) and hydrophobic (water repellent) forms. In some embodimentsof the invention, filter element 214 comprises a support layer and anacrylic co-polymer membrane formed on the support layer. Preferably thewound dressing 100 according to certain embodiments of the presentinvention uses microporous hydrophobic membranes (MHMs). Numerouspolymers may be employed to form MHMs. For example, the MHMs may beformed from one or more of PTFE, polypropylene, PVDF and acryliccopolymer. All of these optional polymers can be treated in order toobtain specific surface characteristics that can be both hydrophobic andoleophobic. As such these will repel liquids with low surface tensionssuch as multi-vitamin infusions, lipids, surfactants, oils and organicsolvents.

MHMs block liquids whilst allowing air to flow through the membranes.They are also highly efficient air filters eliminating potentiallyinfectious aerosols and particles. A single piece of MHM is well knownas an option to replace mechanical valves or vents. Incorporation ofMHMs can thus reduce product assembly costs improving profits andcosts/benefit ratio to a patient.

The filter element 214 may also include an odor absorbent material, forexample activated charcoal, carbon fiber cloth or Vitec Carbotec-RTQ2003073 foam, or the like. For example, an odor absorbent material mayform a layer of the filter element 214 or may be sandwiched betweenmicroporous hydrophobic membranes within the filter element. The filterelement 214 thus enables gas to be exhausted through the orifice.Liquid, particulates and pathogens however are contained in thedressing.

Similar to the embodiments of wound dressings described above, somewound dressings comprise a perforated wound contact layer with siliconeadhesive on the skin-contact face and acrylic adhesive on the reverse.Above this bordered layer sits a transmission layer or a 3D spacerfabric pad. Above the transmission layer, sits an absorbent layer. Theabsorbent layer can include a superabsorbent non-woven (NW) pad. Theabsorbent layer can over-border the transmission layer by approximately5 mm at the perimeter. The absorbent layer can have an aperture orthrough-hole toward one end. The aperture can be about 10 mm indiameter. Over the transmission layer and absorbent layer lies a backinglayer. The backing layer can be a high moisture vapor transmission rate(MVTR) film, pattern coated with acrylic adhesive. The high MVTR filmand wound contact layer encapsulate the transmission layer and absorbentlayer, creating a perimeter border of approximately 20 mm. The backinglayer can have a 10 mm aperture that overlies the aperture in theabsorbent layer. Above the hole can be bonded a fluidic connector thatcomprises a liquid-impermeable, gas-permeable semi-permeable membrane(SPM) or filter that overlies the aforementioned apertures.

The Wound Dressing Embodiments of FIGS. 3A-5

In certain embodiments, such as described above in relation to FIG. 2B,fluid (for example, wound exudate) is handled by the dressing 100 bypassing through the perforated wound contact layer 222, into thetransmission layer 226, and is then absorbed and retained by theabsorbent layer 221. Fluid is then able to evaporate through thebreathable backing layer 220. However, in some embodiments, such asthose observed during in vitro wound model testing, the absorbent layerfills up with fluid in an unpredictable, and often, non-uniform manner.Therefore, as described above, it may be desirable to prevent fluid fromreaching certain areas of the absorbent layer.

In certain embodiments, fluid saturation of the absorbent layer may beimpeded by applying a glue such as a cyanoacrylate Super Glue (forexample Loctite, by Henkel) onto the backing layer. Herein this sectionand throughout the specification, the term “glue” will be used toindicate an adhesive such as Super Glue or any cyanoacrylate glue.Further, adhesives that may be indicated by the use of the term “glue”include hydrophobic adhesives and adhesives that evolve or release a gascontaining hydrophobic materials.

Application of the glue affects the underlying absorbent layer bypreventing liquid from being absorbed in the area below the glue. Insome embodiments, the glue prevents certain areas of the absorbentmaterial from swelling with fluid, thereby acting as a liquid barrier.Glue may be applied to the backing layer or elsewhere in the dressingvia any suitable method, such as via an applicator tube and/or spraybottle. As will be understood. by one of skill in the art, glue could beapplied to the cover layer, absorbent layer, wound contact layer, and/orthe transmission layer in any manner described herein this section orelsewhere in the specification.

Application of the glue to the topmost cover layer allows gaseousmaterial from the glue to pass through the top film into the absorbentlayer. Such gaseous material may alter the hydrophobicity of theunderlying absorbent layer, thereby affecting the fluid passage throughand within the absorbent layer. In embodiments, the gaseous material maydeposit a hydrophobic residue on the fibers of the absorbent layer.

FIGS. 3A-3B show a top view of an embodiment of a wound dressing 300,similar to the dressings described in FIGS. 2A-2B, with a ring of glue302 that adheres the distal end 304 of the fluidic connector 306 todressing 300. FIG. 3A is a photograph of the topside of the embodimentof the wound dressing while FIG. 3B is an illustration of the same.Liquid was drawn into the dressing 308 and is visible through thebacking layer 310 saturating the absorbent layer 312. However, theliquid bends around the ring of glue 302, even though the glue has beenapplied to the top of the backing layer 310. In embodiments, applicationof glue to the top of the backing layer may beneficially prevent areasof the underlying absorbent layer 312 from becoming saturated andswollen. In embodiments, this prevention of saturation is beneficial asswelling of super absorber particles in this area can occlude thefluidic connection 306, therefore preventing negative pressure delivery.

In certain embodiments, the glue may be located at a variety oflocations on the backing layer. For example, the glue may be applied allthe way to the edge of the opening in the backing layer and/or cover theentire distal end of the fluidic connector to the outer edge of thefluidic connector. As described above, the glue may be applied aroundthe rim of the opening in the form of a ring. In embodiments, the gluemay be applied as a single line or as a series of lines. The glue may beapplied as a spiral or as concentric circles on the backing layer. Incertain embodiments, the glue may be applied as distinct, single linesor multiple lines. The glue may be applied to the underside of thebacking layer in any manner described in relation to the topside of thebacking layer.

In embodiments, the glue may be applied around the periphery of thebacking layer, for example, the entire periphery, 50% of the entirety,or 25% of the entirety. In certain embodiments the glue may be appliedto only a portion of the perimeter of the distal end fluidic connector,for example 25%, 50%, or 75%.The glue may be applied to create channelsin the underlying absorbent layers to channel wound exudate to theopening in the backing layer. In certain embodiments, the glue may beapplied under the applicator portion of the fluidic connector, but notthe fluid passage. In embodiments, the glue may be applied to only theoutermost ring of the applicator portion of the fluidic connector and/orthe glue may be applied to the sealing surface of the fluidic connector.In further embodiments, the glue may be applied on the backing layeraround but not under the fluidic connector.

In certain embodiments, the glue may be applied directly to theabsorbent layer in any manner described herein this section or elsewherein the specification, particularly as described above in relation to thebacking layer. In some embodiments, the glue may be applied directly tothe transmission layer in any manner described herein this section orelsewhere in the specification, particularly as described above inrelation to the backing layer. In embodiments, the glue may be applieddirectly to the wound contact layer in any manner described herein thissection or elsewhere in the specification, particularly as describedabove in relation to the backing layer.

FIGS. 4A-4C are illustrations of embodiments of wound dressings withglue applied in different patterns to the cover layers. However, as willbe understood by one of skill in the art, glue may be applied in thesame or similar patterns to any portion of the wound dressing, forexample: the absorbent layer, the wound contact layer, and/or thetransmission layer.

FIGS. 4A-4C depict embodiments of wound dressings 350, 370, 380 similarto the dressing of FIGS. 2A and 2B. As in FIG. 2A, the wound dressingsof FIGS. 4A-4C may have a fluidic connector 352, distal end 354,applicator 356, fluid passage 358, and absorbent layer 360. However, inembodiments, the wound dressing 350 may contain a layer of glue 362 suchas disclosed herein this section or elsewhere in the specification. Thelayer of glue 362 may be applied to the areas of the backing layeroverlying the outer edge of the absorbent layer, thereby creating aliquid barrier at the peripheral edge of the underlying absorbent layer.In embodiments, the glue may be applied to portions of the backing layerabove the entirety of the outer periphery of the absorbent layer.Alternatively, the glue may be applied to the backing layer overlyingonly one edge, two edges, or three edges of the underlying absorbentlayer. Advantageously, applying glue to the backing layer over the edgesof the absorbent layer may prevent fluid leakage from the absorbentlayer into the remainder of the dressing.

FIG. 4B depicts an embodiment of a wound dressing similar to thedressing of FIG. 4B; however, here the glue may be placed in a differentpattern, in stripes 364 across the width of the backing layer overlyingthe absorbent layer. The stripes may also be applied vertically, wherebythey are aligned with the length of the wound dressing. The stripes maybe curved such that the stripes present a concave or a convex sidetoward the distal end 354. In certain embodiments, the dressing may haveone stripe, two stripes, three stripes, four stripes, five stripes, sixstripes, ten stripes, or more than ten stripes. FIG. 4C depicts anembodiment of a wound dressing similar to the embodiments of FIGS. 4A,4B, and 3A-B. Here the glue 366 is applied as a square around fluidicconnector 352.

As described previously, one of skill in the art will also understandthat the glue could be applied directly to the absorbent layer, thetransmission layer, and/or the wound contact layer in similar patternsas disclosed above in relation to FIGS. 4A-4C.

FIG. 5 shows two images of an embodiment of a wound dressing 400,similar to the dressings of FIGS. 2A-4C. Here, a thin bead of super gluewas used to write “PICO” on the dressing 402, specifically to the top ofthe backing layer. The dressing was then filled with a dye solution 404which gradually revealed the word “PICO” written on the backing layer ofthe dressing. Similar to the glue ring shown in FIGS. 3A-B, applicationof glue to the top of the backing layer prevented areas of theunderlying absorbent layer from becoming saturated. In certainembodiments, application of glue may be used to purposefully preventareas of an absorbent layer (for example, around the distal end of thefluidic connector) from becoming saturated.

The Microscopic Images of FIGS. 6-9

FIGS. 6-9 are images of embodiments of dressings similar to thedressings of FIGS. 2A-4. The dressings were sectioned using a clean pairof scissors and a single edge razor blade. These images were motivatedby certain observations of in vitro wound dressings. After applicationof glue to the port of a PICO dressing, it was observed that in a woundmodel the glued area appeared to repel horse serum, which would normallytrack to the port and block the port, often before the dressing wasfull. For the above observation, the glue was applied between the portand the top film of the dressing and around the cut edges of a hole inthe absorbent layer directly underneath the soft port.

FIG. 6 shows micro-CT images, at two cross-sectional angles, ofembodiments of a dressing 500 similar to the dressings of FIGS. 2A-4C.Here, glue applied over the backing layer of a section of dressing iscompared side-by-side with a section of dressing with a backing layerwith no glue. Apart from the textured appearance of the top film on theglue areas there were no macro structural differences between the areaswith and without glue, in that there is no distinct sign of the fibersbeing bound together.

FIG. 7 is a series of SEM images of an embodiment of a dressing similarto the dressings of FIGS. 2A-5, Here, the backing layer was coated inglue 602. Inspection of the dressing section coated with glue did showthat under the backing layer (with the glue) there were a number offibers 604 and a section of a superabsorber particle (shown in FIG. 7)which had been coated with granular particulates. These granularparticulates are likely hydrophobic residue from the gaseous materialemitted by the glue. The granular particulates were not observed on theflat cellulosic fibers. FIG. 6 further includes construction adhesive606 which was identified based on previous knowledge of similardressings.

FIG. 8 is a further series of SEM images of the wound dressing of FIG.7. As in FIG. 7, glue has been applied to the backing layer of thedressing. Here, granular particulates 608 cover sections of superabsorbent particles, again indicating the presence of materials releasedfrom the glue. FIG. 9 is a series of SEM images of a wound dressing 700,similar to the dressings of FIGS. 7-8, however here no superglue hasbeen applied and no granular particulates are observed.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), and/or all of the steps of any method or process sodisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Theprotection is not restricted to the details of any foregoingembodiments. The protection extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. Furthermore, the features andattributes of the specific embodiments disclosed above may be combinedin different ways to form additional embodiments, all of which fallwithin the scope of the present disclosure.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by those skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

1-16. (canceled)
 17. A wound dressing configured to be positioned over awound site, the wound dressing comprising: a backing layer positionedover an absorbent layer, the absorbent layer comprising a hydrophobicbarrier configured to reduce swelling of the absorbent layer; and anadhesive located on an upper surface of the backing layer, the adhesivepositioned directly over the hydrophobic barrier, the hydrophobicbarrier formed by gaseous hydrophobic material migration from theadhesive through the backing layer.
 18. The wound treatment apparatus ofclaim 17, further comprising a wound contact layer beneath the absorbentlayer and sealed to the backing layer.
 19. The wound treatment apparatusof claim 17, further comprising a source of negative pressure configuredto be in fluid communication with the wound site through the wounddressing.
 20. The wound treatment apparatus of claim 17, wherein theabsorbent layer comprises a vertical hole positioned below an opening inthe backing layer.
 21. The wound treatment apparatus of claim 17,wherein the adhesive is positioned on the backing layer over the entireperiphery of the absorbent layer.
 22. The wound treatment apparatus ofclaim 17, wherein the adhesive is positioned on the backing layer in astripe over a width of the absorbent layer.
 23. The wound treatmentapparatus of claim 17, wherein the adhesive is positioned on the backinglayer in a pattern comprising a plurality of stripes
 24. The woundtreatment apparatus of claim 23, wherein the stripes are parallel. 25.The wound treatment apparatus of claim 23, wherein the stripes arecurved.
 26. The wound treatment apparatus of claim 23, wherein theadhesive is positioned on the backing layer in four stripes over thewidth of the absorbent layer.
 27. The wound treatment apparatus of claim17, wherein the adhesive is positioned on the backing layer in the shapeof a square.
 28. The wound treatment apparatus of claim 27, whereinsquare is positioned on around a distal end of a fluidic connector. 29.The wound treatment apparatus of claim 17, wherein the adhesive ispositioned on the backing layer such that channels are created in theunderlying absorbent layer, the channels configured to channel woundexudate to the opening.
 30. The wound treatment apparatus of claim 17,wherein the adhesive is positioned on the backing layer over an edge ofthe absorbent layer, such that fluid leakage from the absorbent layer isreduced.
 31. The wound treatment apparatus of claim 30, wherein theadhesive is positioned over two or more edges of the absorbent layer.